This invention relates to burners for soaking pit furnaces for steel mills and the like. More particularly, the invention relates to an improvement in a bottom-fired soaking pit furnace in which one centrally located burner extends through the floor of the soaking pit and directs the flame upwardly into the interior of the soaking pit furnace.
Steel ingots produced in steel mills are placed in a soaking pit furnace for heating the ingots to a temperature of about 2400.degree. F. The heated ingots soak at that temperature to uniformly heat them throughout until they are malleable enough to be rolled. In a commonly used soaking pit having a prior art burner, it presently takes from about 3 to 4 hours to heat a steel ingot to a temperature of about 2400.degree. F. and another 4 hours or so to soak the ingot to its malleable condition. Such a prior art burner is used in a bottom-fired soaking pit. The burner includes an upright gas pipe disposed centrally in a relatively wide air flow channel which surrounds the gas pipe. Air flows upwardly through the channel and mixes with gas flowing from the pipe. The burner produces a yellow flame, indicating incomplete combustion of the gas and air. The incomplete combustion results in excessive oxide scale buildup on the surface of the steel ingots. The scale acts as an insulator which increases the time and energy required to heat up and soak the steel ingots. Moreover, the scale buildup on the ingots reduces the weight of high grade steel production per ingot. The layer of oxide scale is removed from the ingots after they are soaked and is used in less profitable lower grade steel.
The present invention provides a burner for soaking pits which produces a continuous clean burning blue flame during use. By avoiding incomplete combustion, the burner of this invention reduces scale buildup on the ingots. This results in greater production of more profitable higher grade steel per ingot. The flame produced by the burner of this invention also burns hotter, which reduces the amount of time required for the ingots to reach their soaking temperature, as well as reducing the soaking time of the ingots. The hotter flame also provides a corresponding energy saving because the amount of gas consumption required to heat each ingot is reduced. Inasmuch as scale buildup is reduced, and the scale can act as an insulator, the amount of heat transferred to the ingots by the burner of this invention is increased, which provides an additional saving in heating and soaking time. By reducing soaking time, production can be increased without additional increase in fuel cost. Further, by avoiding incomplete combustion, air pollution is reduced, and the useful life of the soaking pit burner and furnace structure is extended.